Briggs model KR magneto problems

[Jonathan Widelo]

Hi,
I am working on a Briggs & Stratton model KR serial 8382 type no 60347 with a friend it is on a Locke Lawn Mower. It has excellent compression, I rebuilt the carb, cleaned and painted the gas tank. I cant seem to get a spark out of the mag at all , it will not fire a plug but lights up one of those inline spark testors. I replaced the breaker point and filed them to a mirror finish they were dull from sitting for a long time, I replaced the condensor and still noting , the points line up nice and tight at the gap is set to .020 like it says in the book. I checked the coil with a continuity tester and it tested fine , the windings are in tacked with no cracks.
The plug wire also tested fine, could the flywheel be not as charged as it should be ? how do I further test the coil ? the points open and close could the plunger have any effect on this ? I have never had this much trouble with a Briggs magneto before
can anyone help or give me some suggestions on what to do ? I have run out of option to make this thing run, I wish I could just ad a battery and buzz coil to it
Thanks,
~ Jonathan

[Bill Sherlock]

Jonathan,

If that was my engine, I would take the points over to a grindstone and lightly touch each contact to the stone, making sure to keep the surface flat and not angled. Then reinstall the points and gap to specs. Almost bet that will cure your problem.

I have successfully used this method on several engines that have sat unused for years when all else failed, including filing the points as you indicate you have done.

No doubt there are those who will say this is too drastic a measure, but if the points aren't working as they're supposed to, what have you got to lose besides replacing them if you overdo it on the grindstone? Remember they weren't working in the first place.

Bill

[ldj1002]

You said you painted gas tank, did you paint the whole engine? reason I'm asking is, if you did, you may not be getting a good ground.
L.D.

[Neale Behm]

how far is the spark jumping on the tester you are using? I'm thinking there could be a condenser problem still. You can do a reasonable test on a condenser with an old fashion analog (needle and scale type) ohmeter

[Jonathan Widelo]

Thanks for the replys ,I just painted the gas tank because I had to have the tank cleaned inside in a parts washer and all the paint washed off. I have only used the neon tester and it lights the tester up real bright if its grounded to the spark plug hole
~ Jonathan

[Andrew Mackey]

It sounds like you have the voltage (lights the lamp), but not the current to jump the gap. Try closing the plug gap down to .020. Also try a new plug! The new type plugs are made differently, to accomodaet the new unleaded gas. The new unleaded gasoline will pass electrical current! If the plug gets wet with gas, it will short, especially under compression! Try getting spark with a new plug. If the spark is weak - yellowish, or white, and thready, then the condenser is probably bad. A pale blue or purplish weak spark, usually means bad coil.

[BWegher]

Possible that coil is partially shorted, try removing the armature completely. Measure resistance of spark connection lug to wire lead and should get at least 5000 ohms.
Clean every connection point with wire brush. Get a new spark plug wire with new end connector, should have nearly zero resistance between coil and plug.

[Elden DuRand]

Originally Posted by Jonathan Widelo

I wish I could just ad a battery and buzz coil to it
Thanks,
~ Jonathan

Jonathan:

You could use a buzz coil but the timing would be WAY fast! On the mag, spark occurs when the points open. On the buzz coil, the spark occurs when they close.

Now, even if you use a regular auto coil and condenser, the timing will probably be too fast for you to start the engine without a helper. Because the mag doesn't generate enough voltage to fire the plug until the engine's turning at a fairly good clip, by the time the first spark occurs, the speed is up enough to handle the advanced timing.

With a coil and points, you will get a spark at any reasonable speed short of stopped and it will probably say "Oh, no you don't" when you pull the rope.

With a helper to turn on the ignition after you've given the rope a yank, it should run fine.

With a buzz coil, I don't think even the buddy system would work.

Take care - Elden